Embodiments of the inventive concept relate generally to semiconductor memory devices. More particularly, embodiments of the inventive concept relate to flash memory devices and methods of programming the flash memory devices.
Semiconductor memory devices can be roughly divided into two categories based on whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power. Examples of volatile memory devices include static dynamic random access memory (SRAM) and dynamic random access memory (DRAM). Examples of nonvolatile memory devices include electrically erasable programmable read only memory (EEPROM), ferroelectric random access memory, phase-change random access memory (PRAM), and magnetoresistive random access memory (MRAM).
Flash memory is a type of EEPROM that is widely used in electronic computing systems and many other applications due to its high programming speed, low power consumption, and large storage capacity. Flash memory stores data in an array of memory cells each comprising a charge storage element such as a floating gate or a charge trap layer. In a single level cell (SLC) flash memory, each memory cell stores one bit of data, and in a multi-level cell (MLC) flash memory, at least some memory cells store more than one bit of data. Because MLC flash memories can potentially store much more information than SLC flash memories, researchers continue to seek ways to further develop and improve MLC flash memory technology.